Objectives: This paper describes the prevalence of hypothyroidism, in young children and adolescents, aged less than 18 years, with type 1 diabetes mellitus, in northern India. Materials and Methods: Seventy patients (23 female, 47 male) were screened for hypothyroidism, using serum TSH, as part of a detailed assessment of the clinical profile of children and adolescents with type 1 diabetes in an endocrine centre located in Haryana, northern India. Results: Seven girls were found to have hypothyroidism of varying degree, and two boys had subclinical hypothyroidism. Conclusion: Thus, hypothyroidism is found to be a frequent association with type 1 diabetes mellitus in northern India.

The occurrence of autoimmune disease such as type 1 diabetes mellitus and hypothyroidism is well known. This association has been demonstrated in various Indian cohorts, including those from New Delhi, Kochi, and Tirupati [1],[2],[3] Similar findings have also been reported from other Asian countries. [4],[5]

No work has been done in the northern Indian state of Haryana to assess the prevalence of hypothyroidism in children and adolescents with type 1 diabetes. The aim of this study was to assess the frequency of subclinical and clinical hypothyroidism, both previously diagnosed and undiagnosed, in patients with type 1 diabetes mellitus on follow-up at an endocrine center in Haryana.

Materials and Methods

Seventy children and adolescents with type 1 diabetes, aged less than 18 years, presenting to the endocrine OPD, were enrolled in the study after taking as informed consent, Enrolment was carried out during the month of December 2011. All patients were administered a prestructured questionnaire designed to collect basic clinical data, including details of diabetes, thyroid disorders, and comorbid conditions, presence or absence of goiter, and family history of thyroid disease.

Serum TSH was assessed in all patients, by the chemiluminescence method, using a commercial kit. This was done as part of a screening program which also checked hematological parameters, microalbuminuria, and glycated hemoglobin. Thyroid antibodies were not measured due to resource limitations. The normal range of TSH, as provided by the manufacturer, was 0.45-4.5 mIU/ml.

Goiter was assessed by a qualified endocrinologist, and graded as per the WHO grading system. [6] The same observer assessed all patients for goiter to avoid interobserver bias, Data were stored and analyzed on Microsoft Excel. No statistical significance tests were performed as the cross-sectional, observational nature of the study did not call for any such analysis.

Results

Seventy patients with type 1 diabetes mellitus were included in the study. The cohort comprised 47 boys and 23 girls. The age ranged from 2.5 years to 17 years, while duration of diabetes varied from 3 months to 10 years.

On history taking, two girls were found to be known cases of hypothyroidism, taking L-thyroxin supplementation. Both were found euthyroid on testing. Both had documented coeliac disease as well.

A total of five other patients were found to have biochemical hypothyroidism. These included girls with TSH values of 6.67, 7.84, 8.27, 10.24, and 101.45. None of them volunteered any symptoms on detailed history taking, and were above the 50 th percentile for height and weight, as per current Indian charts. Two boys had subclinical hypothyroidism (TSH 4.77, 8.54).

On examination, none of the boys had a palpable or visible goiter. Four girls out of 23(17.4%) had a goiter. Of these one was diagnosed to have hypothyroidism during the study.

Discussion

This study of children and adolescents with type 1 diabetes mellitus highlights certain characteristics unique to Haryana. The male:female ratio of 47.23 or 2:1 reflects earlier reports from this area which describe an extreme gender unbalance in the prevalence of type 1 diabetes. [7],[8] This may be part of the larger phenomenon of skewed gender rates, and discrimination against girls in this society. It may be due to social limitations, which discourage parents from admitting to the diagnosis of diabetes in their daughters, and create suboptimal health care seeking behavior for girls. This gender ratio contrasts with observations from other parts of the globe. [9]

The prevalence of hypothyroidism (known and freshly diagnosed) in girls has been shown to be 30.5% (7/23). This is higher than the prevalence of goiter in this cohort (17.4%). However, as three of the patients with goiter were euthyroid, the total prevalence of goiter and biochemical hypothyroidism was 43.5% (10/23). In boys, the prevalence of hypothyroidism was much lower, 1.8% (2/53).

The high percentage of undiagnosed hypothyroidism (7/70) (10.0%) in the total cohort, 5/23 (15.0%) in girls and 2/55 (1.8%) in boys, speaks for the need to screen all children with type 1 diabetes with serum TSH. The extremely high TSH in one of the children, who was asymptomatic, underscores this need.

The rates of hypothyroidism documented in this study are higher than those reported by Unnikrishnan, from Kochi, but similar to those from Tirupati and New Delhi. [1],[2],[3] They are much higher than those seen in the Western population. [10],[11] It is important to diagnose and treat thyroid disorders, but especially so in people with diabetes, as this has an impact on insulin requirement and glycemic control. [12],[13] The poor control, as evidenced by high HbA1c levels, in the hypothyroid patients, is proof of this.

Conclusion

This study reports a high prevalence of hypothyroidism in girls, and a lower prevalence in boys, with type 1 diabetes mellitus in northern India. It reinforces earlier data which uncovered a wide gender gap in the prevalence of reported type 1 diabetes, and exposes the high incidence of undiagnosed thyroid dysfunction. Thus, it supports a call for improvement in the quality of health care services, including provision of universal screening for thyroid function in children with type 1 diabetes mellitus.